Vapor lock?

Was driving all day today.. roughly mid 90's and dry here. At 5k feet (Denver).

Had A/C on, in stop an go back roads/side streets with stop lights. Got the the liquor store and went in. Truck ran perfectly fine and idled at ease right before I shut it off to go inside.

Came out 5 minutes later, and truck idled very rough and choppy. I turned it off only to not get it to start. It started roughly 5 minutes later, and as I had it floored it finally got to a very slow crawl so I could get it back into a park space then died. Let it sit for half an hour an started up with no problem.

Being an EFI engine, I doubt it was vapor lock. Vapor lock is usually caused by the fuel line running too close to the manifold and boiling the gas. You may want to check the proximity of your lines to any real hot surface like the exhaust manifold.

However you may have a problem with pressure equalization in the tank. You can fuel starve if the vent system is not working. It can create a negative pressure in the tank. Setting for a while may have let the tank pressure equalize and allowed fuel to flow again. A friend of mine had to make an emergency landing in a field with full tanks that would not feed to the engine due to a plugged tank vent.

i had an 89 bronco that would do roughly the same thing did a little troubleshooting and come to find out that they do get vapor lock the fuel pump in the tank was the culprit it was starting to heat up just enough to vaporize the gas in the line and make the engine run rough also check your vent tubes they can be a problem as well

I thought this was the problem two years ago..I replaced the ECT sensor an it ran fine after that. But this deff seems like a vapor lock issue based on the symtoms. And with a mechanical fuel pump and at high altitudes it's possible.

I'll check the vent tubes, and probably replace the fuel pump when I replace the motor.

the vent tube runs from the relief valve on top of the tank to the carbon canister in the engine compartment. If you are standing at the rear of the truck, it is to the right and slightly behind the sender unit. If you haven't already done it now is a good time to make an access hole in the floor. http://broncozone.co...t-access-panel/